Your Mac can be a Hotspot? Why would you do this?
Kken you have the right idea. If you have a smartphone, making this a hotspot makes sense because you can then use the cell connection to allow your Mac or PC access to the internet.
But why make your Mac a hotspot? It probably doesn't have a cell internet connection. Well many offices like you mentioned do not have WiFi but do have a wired Ethernet connection. Now you can connect to that and create your own WiFi hotsopot.
The Wi-Fi hotspot option is part of the “Internet Sharing” feature in Mac OS X. You'll find it in the System Preferences window. Click the Apple menu, select System Preferences, and click the Sharing icon. Select the “Internet Sharing” option in the list. You’ll now need to select the Internet connection you want to share with the devices.
The one big limitation is that you can’t both be connected to a Wi-Fi network and host a Wi-Fi network at the same time. In the “To computers using” box, enable the Wi-Fi option. This will create a Wi-Fi hotspot, and the Internet connection you selected at the top of the window will be shared with devices that connect to the Wi-Fi network.
Click the “Wi-Fi Options” button at the bottom of the window to configure your Wi-Fi hotspot. Select your preferred network name and the best Wi-Fi channel.
Be sure to click the “Security” box and select “WPA2-Personal” and provide a password. By default, the hotspot will be configured without a password and anyone will be able to connect.